1. Field of the Invention
This invention relates to dispensers especially adapted for dispensing sterile liquids, for instance, liquids which may be used in eye care.
Usually, dispensing containers for eye treatment solutions are yieldable plastic containers, commonly known as squeeze bottles. Such containers are in common use for eye drops to treat dryness, reddening, allergic responses and general eye discomfort as well as for drops or streams of liquids used with contact lenses for the eyes.
When a drop, stream or spray of treatment solution from such a container is dispensed and the squeezing pressure is released, external air and contaminates are drawn back into the container where bacterial growth can take place. It is well known that the treatment solutions themselves may serve as a nutrient medium for bacterial growth.
It has, therefore, been necessary to lace the treatment solution with preservatives. Typical preservative materials include a mercurial compound such as sodium merthiolate (also known as thimerosal); benzalkonium chloride; disodium edetate; sorbic acid; chlorhexidine gluconate; polyaminopropyl biguanide; ethylene diamine tetramine; and sodium sorbate. Because of the irritating nature of some preservatives, there has been a reaction on sensitive tissues on some subjects, a decidedly unacceptable consequence.
There has been a need, therefore, for a dispenser adapted to prevent the build-up and migration of bacteria between the discharge opening and the contents of the container. The present invention provides this by means of a tip-sealing valve for use with a pressurized container.
2. Description of Related Art Including Information Disclosed under .sctn..sctn.1.97 to 1.99
The structures of valves in the prior art do not present characteristics which would make them suitable in the present instance. Typical aerosol valves such as Abplanalp U.S. Pat. No. 2,631,814 and Lapin U.S. Pat. No. 2,704,172 have a passageway between the discharge orifice and the actual valve seat or shutoff point. Such a passageway is known to be a site for accumulation and storage of discharge product, a place where bacteria can breed and grow. No valve in the prior art appears especially designed to fulfil the present need.
Structurally, earlier patents of interest include my own U.S. Pat. No. 3,506,165 issued Apr. 14, 1970. This valve is adapted to dispense glue or other sticky or tacky materials which would tend to clog the outlet orifice. It is also useful in the dispensing of other products, such as whipped cream or toothpaste, wherein it is important that the product not be permitted to accumulate between the valve and the end of the orifice.
My U.S. Pat. No. 3,506,165 disclosed as its nozzle a tipable outer shell having an orifice centrally disposed in its end and enclosing a plug extending upwardly toward the orifice. The plug has a flange on its inner end so that when the outer shell is tipped, the plug is drawn downwardly away from the orifice and permits material to discharge. While the invention of my earlier patent is meritorious, its structure involved the mounting of the shell so as to be tipable requiring a substantial amount of actuating force. This type of actuation is awkward when in application of solutions to the eye.
Another patent of interest not relating to an aerosol valve, is U.S. Pat. No. 4,807,786 to Gueret issued Feb. 28, 1989. In this patent there is disclosed a container presumably a squeeze bottle for a lotion. The container has a fixed cover plate formed with an upward bulb apertured adjacent its tip and the container receives a reciprocable cap formed with a central apertured recess which fits over the bulb. The cap may be raised or lowered to permit contents of the container to discharge out the orifices. Special cam means are provided so that the cap can be raised with one hand.
In the Newby U.S. Pat. No. 2,969,168 issued Jan. 24, 1961 a fixed solid post is surrounded by a movable member having an axial post-receiving cavity with a small orifice at its upper end. When the movable member is down, the post plugs the opening, and when the movable member is raised, the post clears the opening to permit discharge.
The Hammerstein U.S. Pat. No. 1,707,660 issued Apr. 2, 1929 has a peaked cover plate with orifices on either side of the plate and a reciprocable tubular plunger, the lower end of which closes off the orifices. The plunger may be raised to clear the orifices and permit discharge flow.
The LoTurco U.S. Pat. No. 4,739,906 issued Apr. 26, 1988 discloses a squeeze bottle having a fixed upward stem with apertures in its base and a flexible conical nozzle which seals and overlies it. When the container is squeezed, product passes through the apertures causing the conical nozzle to bulge out, breaking the seal and discharging out the nozzle.
My earlier U.S. Pat. No. 3,254,676 issued Jun. 7, 1966 discloses a tilt valve wherein the stem has a head with pivotable side arms and a central valving surface so that an arm may be tilted to move the surface past the outlet and actuate the valve at the same time.
Levers and toggles have been used in the past to operate valves and are disclosed, for instance, in U.S. Pat. Nos. 1,557,127 to Wilkin and 523,254 to Winkley.